Overall objective of the proposed research is to establish what alterations occur in muscle membrane following denervation. After establishing these alterations, attempts will be made to quantitate the differences and determine which alterations are interrelated (e.g., which occurs first and which are secondary) and which alterations are of prime physiologic importance. Specific aims of the research are: (1) to determine the regulation of enzymes likely involved in the metabolism of surface membranes of normal and denervated muscle, and (2) to determine regulation of the synthesis and degradation of surface membrane macromolecular constituents in normal and denervated muscle. Goals for the current year included: (1) defining early increases in autodegradation in denervated muscle, concentrating on the role of proteases degrading muscle protein; (2) defining the molecular species of acetylcholinesterase (by sedimentation coefficients in muscle and denervated muscle); (3) determining what species of acetylcholinesterase (3.9 S, 9.9 S and 16.0 S) were released or altered in denervated skeletal muscle, and (4) determining the multiple forms of cholinesterase which are in normal vs. dystrophic (mouse 129/ReJ-dy) skeletal muscle. BIBLIOGRAPHIC REFERENCES: McLaughlin, J. and H.B. Bosmann (1976). Molecular species of acetylcholinesterase in denervated rat skeletal muscle. Exp. Neurol. 52: 263-271. Chizzonite, R.J., J. McLaughlin and H.B. Bosmann (1977). Multiple forms skeletal muscle acetylcholinesterase from normal and dystrophic mouse (129/ReJ-dy). Fed. Proc. 36: 979 (Abs.).